Re: [PATCH 1/2] cleanup: Add conditional guard support

From: Oleg Nesterov
Date: Thu Nov 02 2023 - 11:57:47 EST

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In reply to: Oleg Nesterov: "Re: [PATCH 1/2] cleanup: Add conditional guard support"
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On 11/02, Oleg Nesterov wrote:
>
> On 11/02, Peter Zijlstra wrote:
> >
> > include/linux/cleanup.h | 52 ++++++++++++++++++++++++++++++++++++++++++++---
>
> interesting... I don't know anything about cleanup.h, will
> read this code and the patch later, but I guess I understand
> the idea.
>
> Stupid/offtopic question... Can't we change guard()
>
> -#define guard(_name) \
> - CLASS(_name, __UNIQUE_ID(guard))
> +#define guard(_name, args...) \
> + CLASS(_name, __UNIQUE_ID(guard))(args)
>
> and update the current users?
>
> To me
>
> guard(rcu);
> guard(spinlock, &lock);
>
> looks better than
>
> guard(rcu)();
> // doesn't match scoped_guard(spinlock, &lock)
> guard(spinlock)(&lock);
>
> And this will make guard() consistent with scoped_guard().

Just in case the kernel builds and botts with the patch below.
The .c files were changed by

perl -wpi~ -e 's/\bguard$\w+\K$$ ($)?/$1 || ", "/ex' kernel/sched/core.c drivers/gpio/gpio-sim.c drivers/hv/hv_balloon.c lib/locking-selftest.c

Oleg.
---

diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
index 44bf1709a648..9f659a966ed9 100644
--- a/drivers/gpio/gpio-sim.c
+++ b/drivers/gpio/gpio-sim.c
@@ -70,7 +70,7 @@ static int gpio_sim_apply_pull(struct gpio_sim_chip *chip,
gc = &chip->gc;
desc = &gc->gpiodev->descs[offset];

- guard(mutex)(&chip->lock);
+ guard(mutex, &chip->lock);

if (test_bit(FLAG_REQUESTED, &desc->flags) &&
!test_bit(FLAG_IS_OUT, &desc->flags)) {
@@ -113,7 +113,7 @@ static int gpio_sim_get(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_sim_chip *chip = gpiochip_get_data(gc);

- guard(mutex)(&chip->lock);
+ guard(mutex, &chip->lock);

return !!test_bit(offset, chip->value_map);
}
@@ -663,7 +663,7 @@ static ssize_t gpio_sim_device_config_dev_name_show(struct config_item *item,
struct gpio_sim_device *dev = to_gpio_sim_device(item);
struct platform_device *pdev;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

pdev = dev->pdev;
if (pdev)
@@ -965,7 +965,7 @@ gpio_sim_device_config_live_store(struct config_item *item,
if (ret)
return ret;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (live == gpio_sim_device_is_live_unlocked(dev))
ret = -EPERM;
@@ -1011,7 +1011,7 @@ static ssize_t gpio_sim_bank_config_chip_name_show(struct config_item *item,
struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
struct gpio_sim_chip_name_ctx ctx = { bank->swnode, page };

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return device_for_each_child(&dev->pdev->dev, &ctx,
@@ -1028,7 +1028,7 @@ gpio_sim_bank_config_label_show(struct config_item *item, char *page)
struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

return sprintf(page, "%s\n", bank->label ?: "");
}
@@ -1040,7 +1040,7 @@ static ssize_t gpio_sim_bank_config_label_store(struct config_item *item,
struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);
char *trimmed;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return -EBUSY;
@@ -1063,7 +1063,7 @@ gpio_sim_bank_config_num_lines_show(struct config_item *item, char *page)
struct gpio_sim_bank *bank = to_gpio_sim_bank(item);
struct gpio_sim_device *dev = gpio_sim_bank_get_device(bank);

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

return sprintf(page, "%u\n", bank->num_lines);
}
@@ -1084,7 +1084,7 @@ gpio_sim_bank_config_num_lines_store(struct config_item *item,
if (num_lines == 0)
return -EINVAL;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return -EBUSY;
@@ -1109,7 +1109,7 @@ gpio_sim_line_config_name_show(struct config_item *item, char *page)
struct gpio_sim_line *line = to_gpio_sim_line(item);
struct gpio_sim_device *dev = gpio_sim_line_get_device(line);

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

return sprintf(page, "%s\n", line->name ?: "");
}
@@ -1121,7 +1121,7 @@ static ssize_t gpio_sim_line_config_name_store(struct config_item *item,
struct gpio_sim_device *dev = gpio_sim_line_get_device(line);
char *trimmed;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return -EBUSY;
@@ -1149,7 +1149,7 @@ static ssize_t gpio_sim_hog_config_name_show(struct config_item *item,
struct gpio_sim_hog *hog = to_gpio_sim_hog(item);
struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

return sprintf(page, "%s\n", hog->name ?: "");
}
@@ -1161,7 +1161,7 @@ static ssize_t gpio_sim_hog_config_name_store(struct config_item *item,
struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
char *trimmed;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return -EBUSY;
@@ -1216,7 +1216,7 @@ gpio_sim_hog_config_direction_store(struct config_item *item,
struct gpio_sim_device *dev = gpio_sim_hog_get_device(hog);
int dir;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return -EBUSY;
@@ -1276,7 +1276,7 @@ gpio_sim_line_config_make_hog_item(struct config_group *group, const char *name)
if (strcmp(name, "hog") != 0)
return ERR_PTR(-EINVAL);

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

hog = kzalloc(sizeof(*hog), GFP_KERNEL);
if (!hog)
@@ -1334,7 +1334,7 @@ gpio_sim_bank_config_make_line_group(struct config_group *group,
if (ret != 1 || nchar != strlen(name))
return ERR_PTR(-EINVAL);

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return ERR_PTR(-EBUSY);
@@ -1387,7 +1387,7 @@ gpio_sim_device_config_make_bank_group(struct config_group *group,
struct gpio_sim_device *dev = to_gpio_sim_device(&group->cg_item);
struct gpio_sim_bank *bank;

- guard(mutex)(&dev->lock);
+ guard(mutex, &dev->lock);

if (gpio_sim_device_is_live_unlocked(dev))
return ERR_PTR(-EBUSY);
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index e000fa3b9f97..a8954db4cb1c 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -784,7 +784,7 @@ static void hv_online_page(struct page *pg, unsigned int order)
struct hv_hotadd_state *has;
unsigned long pfn = page_to_pfn(pg);

- guard(spinlock_irqsave)(&dm_device.ha_lock);
+ guard(spinlock_irqsave, &dm_device.ha_lock);
list_for_each_entry(has, &dm_device.ha_region_list, list) {
/* The page belongs to a different HAS. */
if ((pfn < has->start_pfn) ||
@@ -803,7 +803,7 @@ static int pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt)
unsigned long residual, new_inc;
int ret = 0;

- guard(spinlock_irqsave)(&dm_device.ha_lock);
+ guard(spinlock_irqsave, &dm_device.ha_lock);
list_for_each_entry(has, &dm_device.ha_region_list, list) {
/*
* If the pfn range we are dealing with is not in the current
@@ -2068,7 +2068,7 @@ static void balloon_remove(struct hv_device *dev)
#endif
}

- guard(spinlock_irqsave)(&dm_device.ha_lock);
+ guard(spinlock_irqsave, &dm_device.ha_lock);
list_for_each_entry_safe(has, tmp, &dm->ha_region_list, list) {
list_for_each_entry_safe(gap, tmp_gap, &has->gap_list, list) {
list_del(&gap->list);
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index 53f1a7a932b0..1d13792a3d85 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -105,8 +105,8 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
#define DEFINE_GUARD(_name, _type, _lock, _unlock) \
DEFINE_CLASS(_name, _type, _unlock, ({ _lock; _T; }), _type _T)

-#define guard(_name) \
- CLASS(_name, __UNIQUE_ID(guard))
+#define guard(_name, args...) \
+ CLASS(_name, __UNIQUE_ID(guard))(args)

#define scoped_guard(_name, args...) \
for (CLASS(_name, scope)(args), \
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 802551e0009b..81acd7811db3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1097,7 +1097,7 @@ int get_nohz_timer_target(void)

hk_mask = housekeeping_cpumask(HK_TYPE_TIMER);

- guard(rcu)();
+ guard(rcu);

for_each_domain(cpu, sd) {
for_each_cpu_and(i, sched_domain_span(sd), hk_mask) {
@@ -1827,7 +1827,7 @@ static int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
int old_min, old_max, old_min_rt;
int result;

- guard(mutex)(&uclamp_mutex);
+ guard(mutex, &uclamp_mutex);

old_min = sysctl_sched_uclamp_util_min;
old_max = sysctl_sched_uclamp_util_max;
@@ -3440,8 +3440,8 @@ static int migrate_swap_stop(void *data)
src_rq = cpu_rq(arg->src_cpu);
dst_rq = cpu_rq(arg->dst_cpu);

- guard(double_raw_spinlock)(&arg->src_task->pi_lock, &arg->dst_task->pi_lock);
- guard(double_rq_lock)(src_rq, dst_rq);
+ guard(double_raw_spinlock, &arg->src_task->pi_lock, &arg->dst_task->pi_lock);
+ guard(double_rq_lock, src_rq, dst_rq);

if (task_cpu(arg->dst_task) != arg->dst_cpu)
return -EAGAIN;
@@ -3734,7 +3734,7 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)

__schedstat_inc(p->stats.nr_wakeups_remote);

- guard(rcu)();
+ guard(rcu);
for_each_domain(rq->cpu, sd) {
if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
__schedstat_inc(sd->ttwu_wake_remote);
@@ -3940,9 +3940,9 @@ void wake_up_if_idle(int cpu)
{
struct rq *rq = cpu_rq(cpu);

- guard(rcu)();
+ guard(rcu);
if (is_idle_task(rcu_dereference(rq->curr))) {
- guard(rq_lock_irqsave)(rq);
+ guard(rq_lock_irqsave, rq);
if (is_idle_task(rq->curr))
resched_curr(rq);
}
@@ -4198,7 +4198,7 @@ bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success)
*/
int try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
{
- guard(preempt)();
+ guard(preempt);
int cpu, success = 0;

if (p == current) {
@@ -5730,7 +5730,7 @@ static void sched_tick_remote(struct work_struct *work)
* of when exactly it is running.
*/
if (tick_nohz_tick_stopped_cpu(cpu)) {
- guard(rq_lock_irq)(rq);
+ guard(rq_lock_irq, rq);
struct task_struct *curr = rq->curr;

if (cpu_online(cpu)) {
@@ -6297,8 +6297,8 @@ static bool try_steal_cookie(int this, int that)
unsigned long cookie;
bool success = false;

- guard(irq)();
- guard(double_rq_lock)(dst, src);
+ guard(irq);
+ guard(double_rq_lock, dst, src);

cookie = dst->core->core_cookie;
if (!cookie)
@@ -6410,7 +6410,7 @@ static void sched_core_cpu_starting(unsigned int cpu)
struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
int t;

- guard(core_lock)(&cpu);
+ guard(core_lock, &cpu);

WARN_ON_ONCE(rq->core != rq);

@@ -6449,7 +6449,7 @@ static void sched_core_cpu_deactivate(unsigned int cpu)
struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
int t;

- guard(core_lock)(&cpu);
+ guard(core_lock, &cpu);

/* if we're the last man standing, nothing to do */
if (cpumask_weight(smt_mask) == 1) {
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 6f6a5fc85b42..724132f6109e 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -2527,8 +2527,8 @@ DEFINE_LOCK_GUARD_0(RCU_SCHED, rcu_read_lock_sched(), rcu_read_unlock_sched())
static void __maybe_unused inner##_in_##outer(void) \
{ \
/* Relies the reversed clean-up ordering: inner first */ \
- guard(outer)(outer_lock); \
- guard(inner)(inner_lock); \
+ guard(outer, outer_lock); \
+ guard(inner, inner_lock); \
}

/*

Next message: Edgecombe, Rick P: "Re: [PATCH v2 1/1] swiotlb: do not free decrypted pages if dynamic"
Previous message: Thomas Gleixner: "Re: [syzbot] [ext4?] general protection fault in hrtimer_nanosleep"
In reply to: Oleg Nesterov: "Re: [PATCH 1/2] cleanup: Add conditional guard support"
Next in thread: Peter Zijlstra: "Re: [PATCH 1/2] cleanup: Add conditional guard support"
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